Carburizing mechanism



D. V. SCULLEN CARBURIZING MECHANISM Filed Jan. 12, 1959 May 6, 1941.

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Patented May 6, 1941 CARBURIZING MECHANISM Daniel V. Scullen, Cohoes,'N.Y., assignor to General Motors Corporation, Detroit, Mich., acorporation of Delaware Application January 12, 1939, Serial No. 250,602

4 Claims.

This invention relates to carburizing mechanisms for iron and steelarticles, and more particularly to a furnace for case hardening smallarticles in bulk.

An object is to provide an improved carburizing mechanism whichfacilitates an even distribution of the carburizing gases and produces afast, uniform carburizing operation simultaneously on a multiplicity ofWork pieces.

Another object is to provide a retort having a plurality of carburizingchambers so constructed as to uniformly distribute the work, and whichproduces even heating of the work and uniform ly presents the worksurfaces to the carburizing gas.

A further object resides in the provision of a reinforcedmulti-chambered retort so constructed that it does not tend to distortor crack when subjected to extreme temperature changes, and whichreduces the tendency of injury to the work during a carburizingoperation.

To these ends and also to improve generally upon devices of thecharacter indicated, the invention consists in the various mattershereinafter described and claimed.

In the accompanying drawings:

Figure 1 is a longitudinal section through my carburizing mechanismtaken substantially along the line ll' of Figure 3;

Figure 2 is an enlarged fragmentary view showing the coupling in theinfeed duct;

Figure 3 is a view of the efliuent end of my carburizing mechanism; and

Figure 4 is a fragmentary cross section taken substantially along theline l4 of Figure 1.

Generally stated, my carburizing mechanism is herein shown in the formof a furnace l0 supported by the transversely extending co-axial pivotsll received within the frames [2 at each side of the furnace so that thefurnace may be longitudinally tilted to facilitate loading and unloadingof the work. My furnace contains the substantially cylindrical rotatableretort l3 provided with an intermediate work-holding portion I4 which isdivided into a plurality of work-carburizing chambers l5, each of whichmay receive a large number of work pieces loosely mounted in bulk for acarburizing operation. I have found that dividing the work-holdingportion I 4 into a plurality of chambers greatly increases the efficientand reliable operative capacity of the retort, since the carburizing gasmay be more uniformly distributed through each of these chambers l5, andthe rotation of the retort evenly and loosely distributes the work ineach chamher, which results in a better and more uniform heating of thework without injury to the work while the carburizing gas contacts allof the work surfaces to simultaneously produce the same even depth ofcase-hardening on each work piece.

In the illustrated embodiment, the tubular work holding portion M, ofreduced diameter, is divided into the four sector-shaped carburizingchambers [5 provided with the common transverse end wall I8 andseparated by the substantially radial walls l9 which are joined to theend wall l8 and extend through the length of the work holding portion l4between the outer retort Wall and a central hollow core 2| that axiallyprojects from the end wall l8 for the entire length of the carburizingchambers. The outer end of the core H is closed at 22, and the tubularretort ends 23 and 24, which respectively and freely extend through andsubstantially close the cylindrical apertures 25 and 26 in the furnaceends, are rotatably and respectively supported by the sets of rollers 28and 29 mounted on the shafts 3| and 32 projecting from the ends of thefurnace I0. The rollers 29 fit within the peripheral grooved track 33 inthe head 34 secured as by the screws 35 to the retort end 24, and asuitably driven sprocket 3B is secured to the head 34 so that the retortmay be rotated within the furnace. The rollers 28 at the retort end 23engage the cylindrical outer retort wall in spaced relation to theannular end flange 31 so that the retort may longitudinally slide aswell as rotate on these rollers and expansion and contraction of theretort will not be restricted under influence of temperature changes.

A supply duct 40, which carries a suitable carburizing gas, isuniversally and rotatably connected through a coupling generallyindicated at 4| to the feed pipe 42 that axially extends through thesprocket 36 and the retort end 24. The inner end of the pipe 42 isthreaded Within the bore that extends through the boss 43 on the domeshaped cap 44. The cap, which has a stepped rim 45 fitted "against theannular seat 45 adjacent the outer face of the wall l8, cooperates withthe wall |8 to provide the gas expansion chamber 48 that receives thecarburizing gas from the infeed pipe 42 and uniformly distributes thiscarburizing gas into the carburizing chambers l5 through the ports 50 inthe Wall l8. Each of these ports 50 is preferably substantiallycentrally located with respect to its chamber l5 so that the gas will beuniformly distributed into carburizing chambers and will evenly contactwith the work surfaces.

The coupling 4| which may be of various forms, is here shown as having ahousing 55 at the end of the duct 48 and provided with a bore 56. Atubular connector 57, secured to the outer end of the pipe 42,terminates in a parti-spherical head '59 located within the bore 56 andwhich universally engages the cup-shaped seat 60 of a washer 6!rotatably and slidably mounted in the bore 56. A nut 63 threaded on thehousing 55 has an in-turned' ,flange 54 against which the washer BIseats, and a coiled spring 65, engaged at one end in a recess 66 in thehead 59, is com-i tom of the bore 56 to maintain the universal seatedrotatable relation of the head 59 in the washer 6|, so that the retortmay be rotatably driven without transmitting its movement to the ductAll.

fits within the retort end 23 and has an inner dome-:shaped wall?! whichforms a closure for each of the carburizing chambers l5. This wall H,which closely overlies the core end 22 to separate the loading ends ofthe chambers I5, has an annular bevelled face 12 removably seatedagainst a similar face 13 in the retort wall at the end of thecarburizing chambers. An end flange M on the member 70 is slotted at T5to respectively receive the clamping screws 16 pivotally secured to theflange 31, and the thumb nuts Tl on the screws 16 engage the flange itand removably clamp the member 10 in seated position. The effluent pipes18 extend through the end wall ll and respectively communicate with eachof the carburizing chambers it so that the spent carburizing gases mayfreely exhaust from the work. The closure member "m and the retort end24 between the cap as and the head 3'3 are each filled with a suitableheat insulating material 19 such as asbestos or a refractory material.The furnace i is provided with the intermediate heating cha'mber libsurrounding the work holding portion I4, and, in the present instance,the heating medium is shown in the form of a series of electricallyenergized grids 8i supported in spaced relation to the inner furnacewall. However, it will be appreciated that any suitable form of heatingmay be employed. The heating chamber 89 has a refractory lining 82surrounded by a suitable heat -insulating material 83, such as asbestosor the like, held in position by an outer casing 85.

I claim:

1. In a device-of the character indicated, a retort provided with aplurality of work-holding chambers, a transverse wall closing saidchambers at one end and having ports respectively extending therethroughinto said chambers, a second wall engaging the retort in spaced relationto said first wall and providing a gas expansion chamber between saidwalls, and a duct communicating with said expansion chamber through saidsecond wall; substantially as described.

2. In a device of the character indicated, a retort provided with aplurality of adjacent work holding chambers, a transverse wall closingone pressed between the connector 51 and the botend of said chambers andhaving ports respectively communicating with said chambers, aperipherally disposed seat in the retort adjacent said wall, adome-shaped head engaging said seat and spaced from said wall to providea gas expansion chamber at one end of said ports, and a ductcommunicating with said expansion chamber through said head;substantially as described.

3. In a device of the character indicated, a retort having anintermediate work receiving portion provided with a plurality ofadjacent sectorshaped work-holding chambers, a transverse wall closingone end of said chambers and having ports respectively extendingtherethrough into said chambers, an annular seat at the other end ofsaid chambers, a second wall in spaced relation to said other wall andproviding a gas expansion chamber between said walls communieating withsaid ports, a duct communicating with said expansion chamber throughsaid second wall, a closure member removably engageable with said seatfor closing the other end of the work-holding chambers, and efiluentducts respectively communicating with the work holding chambers throughsaid closure member; substantially as described.

4. In a carburizing furnace, a rotatable tubular retort having anintermediate reduced work receivin portion, a transverse wall closingone end of said portion, the other end of said portion terminating in anannular seat within the retort, a hollow core opening through andlongitudinally extending from said transverse wall through said portion,the other end of said core being closed, longitudinally disposed wallsconnected to said core and to said transverse wall and dividing theintermediate work receiving portion into sector-shaped work holdingchambers, and a closure member closely overlying the closed end of thecore andremovably mounted in the retort against said seat to close saidchambers.

DANIEL V. SCULLEN.

